Tube heat exchanger



p l 21. 1970 A. A. RQNNHOLM ET AL 3,507,323

TUBE HEAT EXCHANGER Filed Oct. 10, 1968 United States Patient 3,507,323TUBE HEAT EXCHANGER Arvi Aiol Ronnholm, Juhani Jyry Kaartamo, and JuhaniEevertti Puurunen, Pori, Finland, assignors to W. Rosenlew & Co., A.B.,Pon', Finland, a corporation of Finland Filed Oct. 10, 1968, Ser. No.766,557 Claims priority, application Sweden, Oct. 27, 1967, 1 755/67Int. Cl: rzsr 9/22 US. Cl. 165--145 1 Claim ABSTRACT OF THE DISCLOSUREBACKGROUND OF THE 'INVENTION Tube heat exchanger or heating units withdouble tubes are previously known. In a prior known construction theouter of the double tubes is closed at its upper end, so that the mediumwill flow in one direction through the inner tube and then back in theopposite direction through the outer tube the outer and inner tubesbeing secured to their respective tube plates at the same end of thetubes. Heat transfer from the heating medium to the medium to be heatedthus takes place only from one side of the heated medium through thetube walls. In another prior known construction the outer tubes aresecured between two tube plates and open at both ends, while the innertubes are arranged in the same manner as in the embodiment describedabove, in the form of double tubes closed at one end and secured totheir respective tube plates. Since the medium to be heated flowsthrough the outer tubes, heat exchange to the same will take place fromboth sides and thus more effectively than in the first mentioned case.The construction becomes, however, considerably more complicated in thatfour tube plates are required, which, of course, complicates the sealingproblems as well as supervision, cleaning and repair.

According to another proposal double tubes are inserted in two tubeplates only, the inner tubes opening through the walls of the outertubes into the space between the tube plates. The inner tubes have beenprovided with longitudinal ri'bs which renders the construction rathercomplicated and expensive and also vulnerable for incrustation. In thisprior known heat exchanger the circulation of heating medium through theinner tubes has been poor which fact has adversely affected the heattransfer.

SUMMARY OF THE INVENTION The present invention provides a heat exchangerwith effective heat transfer from the heating medium to the heatedmedium and of a more simple construction than that of prior known heatexchangers of corresponding type. In the heat exchanger according to theinvention there are standard outer and inner tubes, the inner tubesbeing provided with inlets resp. outlets for the heating medium, saidinlets resp. outlets extending through the wall of the adjacent outertube and opening at opposite sides of the tube plates with respect tothe inlets resp.

Patented Apr. 21, 1970 outlets of the outer tubes. According'to theinvention an effective flow of heating medium through the inner tubes isprovided by introducing the heating medium into the space surroundingthe outer tubes through an annular slot, a baflie plate being insertedin said slot for the distribution of heating medium between said spacesurrounding the outer tubes on one hand and the inner tubes on the otherhand.

A heat exchanger according to the invention thus has only two tubeplates, and one outer tube with one inner tube form a unit, whichfacilitates tube replacement. Also with respect to tube connections thenew heat exchanger is simplified, in that only one inlet resp. oneoutlet for the heating medium is required. With respect to tube heatexchangers with heat transfer only at one side, the inventive heatexchanger has the great advantage, that it is possible at constantvolume to increase the capacity of the heat exchanger by from 50 to 60percent, or inversely, at the same capacity to decrease the dimensionsof the heat exchanger correspondingly.

DESCRIPTION OF THE DRAWING The accompanying drawing shows schematicallyone embodiment of the invention in longitudinal section.

DETAILED DESCRIPTION 'In the drawing the numeral 1 denotes a cylindricalhousing, provided with end portions 2 and 3, having inlet and outletconnections 4 and 5 respectively for the medium to be heated which flowsin the direction indicated by arrows. Two tube plates 6 and 7 areprovided, in the housing, to which plates a plurality of tubes 8 aresecured in any suitable manner prior per se known, such as by expanding.Each tube 8 is provided with a substantially coaxially situated innertube 9 which has an inlet 10 extending through the wall of the outertube 8 and an outlet 11 arranged in a corresponding manner. Said inletsand outlets can be provided eg by cutting the tube ends at an angle of45 and by welding the severed ends together with the tube together withthe end portions only just can be inserted into an outer tube 8. Thelatter is provided with openings for the end portions 10, 11,correspondingly spaced, and the end portions are passed so far into theopenings that the tube 9 will be substantially coaxial with the tube 8,after which the end portions are secured by welding, and any protrudingportions are removed. Thus an outer tube 8 and an inner tube 9 form afixed unit. The medium to be heated is arranged to flow in the spacebetween the tubes 9 and 8. The end portions constitute hereby naturallya certain flow obstruction, but by virtue of their flow favoringcircular cross section this obstruction is of no substantial practicalimportance.

The heating medium which suitably can consist of steam, is arranged toflow on the one hand on the outside of the outer tubes 8 and on theother hand through the inner tubes 9, 10, 11. The drawing shows a steampipe 13 connected to a distributing hood 12 on the housing 1, while thenumeral 14 denotes a condensate outlet from the space between the tubeplates 6, 7 in the housing 1. To ensure a uniform distribution of thesteam between the inner tubes 9, 10, 11 and the space around the outertubes 8, a distributing plate 15 is provided below the openings 10 atsuch a level that the ratio between the openings formed at the peripheryabove and below the distributing plate will give the desired uniformdistribution.

The heat exchanger according to the invention may further be partitionedinto sections, and be provided with guiding means so that the medium tobe heated, after having flown through one section, will be guided backthrough another section for further heating.

We claim:

1. A heat exchanger comprising an elongated casing, two partitionsextending transversally in said casing at a distance from each other anddefining end compartments at the opposite ends of said casing, aplurality of parallel outer tubes having open ends extending from oneend compartment through said partitions into the other end compartment,an inner tube extending coaxially within each of said outer tubes, theends of said inner tube opening through the Wall of said outer tube intothe space be- 10 tween and adjacent to said partitions, an inlet for aheat receiving medium connected to one of said end compartments, anoutlet for said medium connected to the other end compartment, a jackethaving an inlet for a heat delivering medium encircling said casingadjacent to one of said partitions, said partition and said casingforming between them a substantially annular slit, an outlet for saidheat delivering medium connected to said casing adjacent to the other ofsaid partitions, and a plate extending substantially in parallel withsaid partitions between said outer tubes into said annular slit for thedistribution of said heat delivering medium on said inner tubes and thespace surrounding said outer tubes respectively.

References Cited UNITED STATES PATENTS 2,740,803 4/ 1956 Dorschner1651G6 3,170,511 2/1965 Guthrie 165154 FOREIGN PATENTS 1,274,618 9/ 1960France.

15 LLOYD L. KING, Primary Examiner C. SUKALO, Assistant Examiner US. Cl.X.R.

